A dummy Tomahawk missile being transported back to a naval base in Virginia was knocked off target when a tractor-trailer carrying it through the Big Apple jackknifed in a Bronx highway collision, police said.

The nearly-20-foot-long, 3,000-pound projectile toppled off the flatbed onto the road when a second truck smacked into it from behind at about 4:45 a.m. on Interstate 95 near the Hutchinson River Parkway.

No one was seriously injured in the accident, which began when the missile-carrying vehicle broke down in the center lane of southbound I-95, also known as the New England Thruway.

Bomb Squad cops responded and quickly spotted the word “inert” emblazoned on the side of the replica, which is used for military training.

Police transported the Tomahawk – which first came to wide public attention in the first Gulf War – to the NYPD Bomb Squad facility at nearby Rodman’s Neck to await pickup by the Navy.

“The information given to us was that the test missile had no explosives, fuel or guidance systems,” said Joseph Green, a spokesman for the Federal Bureau of Alcohol, Tobacco, Firearms and Explosives. “It’s considered a training device.”

The dummy missile – often referred to as a “TOTEM,” for Tomahawk Test Missile – is used during Navy practice drills.

“It’s the same shape and size as a real missile. It’s used in training on how to load the torpedo tubes on submarines,” said Lt. John Gay, a spokesman for the Navy.

The TOTEM can also be used to help calibrate launching systems because it has similar dimensions to the original.

The missile was being transported back to a naval base in Norfolk, Va., from a base in Newport, R.I., where it was on loan for use in the testing of new equipment, Gay said.